Drive arrangement for electric power assisted bicycle

Abstract

A drive arrangement for an electrically power assisted bicycle, wherein the electrical power assist components are comprised of an electric motor and transmission as one unit and a battery as another unit, with the electric motor and transmission being disposed on one side of and relatively low relative to a manual crank axis and the battery case is disposed on the rear side of the crank axis to improve fore and aft balance while maintaining a low center of gravity.

What is claimed is:  
     
       1. An electrically power assisted bicycle comprised of a frame, a front wheel dirigibly supported by said frame, a rear wheel journaled for rotation by said frame, a seat carried by said frame for accommodating a rider, a pedal assembly journaled by said frame for rotation about a transverse crank axis for operation by a rider seated on said seat, a drive coupling said pedal assembly to said rear wheel for manual driving of said rear wheel, an electric power assist mechanism for transmitting a driving force to said rear wheel through said drive and comprised of an electrical motor and a transmission for transferring motive power from said electrical motor to said drive disposed longitudinally entirely on the forward side of said crank axis, said frame comprising a head pipe dirigibly supporting said front wheel and a main frame member extending rearwardly and downwardly toward said crank axis and a seat pillar extending upwardly and rearwardly from a lower end adjacent said crank axis and supporting said seat, said electrical motor and transmission being supported beneath said main frame member and having an output shaft extending generally parallel to and beneath said main frame member, and battery means for providing the only source of electrical power to said electrical motor and disposed longitudinally entirely on the rear side of said crank axis and substantially forwardly of the rotational axis of said rear wheel. 
     
     
       2. The electrically power assisted bicycle of claim  1 , wherein the battery means is disposed to the rear of and generally parallel to the seat pillar. 
     
     
       3. The electrically power assisted bicycle of claim  2 , wherein the battery means is disposed beneath the seat and further including means for movably supporting said seat for accessing said battery. 
     
     
       4. The electrically power assisted bicycle of claim  3 , further including a pair of auxiliary seat tubes disposed to the rear of said seat pillar and to the rear and on opposite sides of the battery means. 
     
     
       5. The electrically power assisted bicycle of claim  3 , wherein the seat is supported on the seat pillar by a first portion slidably supported relative to the seat pillar and a second portion also slidably received in the seat pillar and pivotally connected to the first portion for telescopic movement of the first and second portions and pivotal movement of the first portion relative to the second portion. 
     
     
       6. The electrically power assisted bicycle of claim  5 , wherein the electrical motor is disposed forwardly of the crank axis and is supported beneath the main frame member and has an output shaft extending generally parallel to and beneath said main frame member. 
     
     
       7. An electrically powered bicycle comprised of a frame assembly, a front wheel dirigibly supported by said frame assembly, a rear wheel journalled for rotation by said frame assembly, said frame assembly being comprised of an upstanding seat pillar carrying a seat at the top thereof for accommodating a rider, an electric motor carried by said frame assembly for powering said rear wheel, and an open topped battery case carried by said frame assembly to the rear of said seat pillar and extending parallel to said seat pillar for accommodating a battery for powering said electric motor, said battery case being disposed beneath said seat and being adapted to receive the battery upon movement thereof in a direction generally parallel to said seat pillar. 
     
     
       8. The electrically powered bicycle of claim  7 , wherein the seat is movably supported relative to the seat pillar for accessing the battery case for battery removal. 
     
     
       9. The electrically powered bicycle of claim  8 , wherein the seat is supported on the seat pillar by a first portion slidably supported relative to the seat pillar and a second portion also slidably received in the seat pillar and pivotally connected to the first portion for telescopic movement of the first and second portions and pivotal movement of the first portion relative to the second portion. 
     
     
       10. An electrically power assisted bicycle comprised of a frame element comprised of a head pipe, a down pipe extending downwardly and rearwardly from said head pipe and a seat pipe extending generally vertically upwardly from a iuncture with a rear portion of said down pipe, a front wheel dirigibly supported by said head pipe, a rear wheel journaled for rotation by said frame element, a seat carried by said seat pipe for accommodating a rider, a pedal assembly journaled by said frame element for rotation about a transverse crank axis for operation by a rider seated on said seat, said crank axis being contiguous to the juncture of said down pipe and said seat pipe, a drive coupling said pedal assembly to said rear wheel for manual driving of said rear wheel, and an electric power assist mechanism for transmitting a driving force to said rear wheel through said drive and comprised of an electrical motor disposed longitudinally along one of said down and seat pipes and entirely on one side of said crank axis and battery means for providing the only source of electrical power to said electric motor and disposed longitudinally along the other of said down and seat pipes and entirely on the other side of said crank axis, said seat pipe being disposed forwardly of said crank axis and the one of said electrical motor and said battery means that is longitudinally disposed along said seat pipe is disposed to the rear of the seat pipe and between the seat pipe and the rear wheel. 
     
     
       11. An electrically power assisted bicycle comprised of a frame, a front wheel dirigibly supported by said frame, a rear wheel journaled for rotation by said frame, a seat for accommodating a rider, said seat being carried by a seat post of said frame disposed forwardly of a rear fender covering at least in part said rear wheel, a pair of back stays extending rearwardly from said seat post and on opposite sides of said rear fender, a pedal assembly journaled by said frame for rotation about a transverse crank axis for operation by a rider seated on said seat, a drive coupling said pedal assembly to said rear wheel for manual driving of said rear wheel, and an electric power assist mechanism for transmitting a driving force to said rear wheel through said drive and comprised of an electric motor, transmission means for coupling an output shaft of said electric motor to said drive for driving said rear wheel, battery means for providing the only source of electrical power to said electric motor, and means for supporting said battery means in the area longitudinally spaced between said seat post and said rear fender and in the area transversely between said back stays for protection of said battery means. 
     
     
       12. The electrically power assisted bicycle of claim  11  wherein the battery means is disposed in a generally upstanding direction to the rear of the crank axis and beneath the seat and is inserted and removed from the bicycle in directions parallel to the seat post. 
     
     
       13. The electrically power assisted bicycle of claim  11  wherein the battery means is detachably received at least in part within a battery case also positioned in the area between the seat post, the rear fender and the back stays. 
     
     
       14. The electrically power assisted bicycle of claim  13  wherein the battery means has a disconnectable connection to the electric motor through a terminal carried by the battery case. 
     
     
       15. The electrically power assisted bicycle of claim  14  wherein the disconnectable connection between the battery means and the terminal carried by the battery case is automatically connected and disconnected upon insertion and removal of the battery means to and from the battery case. 
     
     
       16. An electrically power assisted bicycle comprised of a frame, a front wheel dirigibly supported by said frame, a rear wheel journaled for rotation by said frame, a seat for accommodating a rider, said seat being carried by said frame, a pedal assembly journaled by said frame for rotation about a transverse crank axis for operation by a rider seated on said seat, a drive coupling said pedal assembly to said rear wheel for manual driving of said rear wheel, and an electric power assist mechanism for transmitting a driving force to said rear wheel through said drive and comprised of an electric motor, transmission means for coupling an output shaft of said electric motor to said drive for driving said rear wheel, a battery case carried by said frame, and battery means detachably supported in said battery case, said battery means having a disconnectable connection to said electric motor through a terminal carried by said battery case, said disconnectable connection between said battery means and said terminal carried by the battery case is automatically connected and disconnected upon insertion and removal of the battery means to and from the battery case. 
     
     
       17. The electrically power assisted of claim  16  wherein the battery case includes an open member having an end wall supporting the terminal and adapted to receive at least an end of the battery means.